In recent years, so-called “mobile games”, which operate in mobile apparatuses such as mobile phones, have been widely played, and a geometry process is critical in developing the games. Such mobile games include games in which a three-dimensional object is modeled by a combination of polygonal figures called polygons, and rendered on a display. The modeled three-dimensional object is referred to as “polygon mesh” because of a structure thereof in which polygons are filled in a mesh pattern. The polygon mesh is expressed by multiple vertices and edges that connect the multiple vertices. To simplify the calculation, triangles are usually selected to be used as a polygon. When rendering a polygon mesh, it is necessary to perform a vertex process and a polygon process. The vertex process is a process for performing coordinate transformation and illuminance calculation on the vertices of a polygon. The polygon process is for performing calculation with respect to the gradients of the edges of a polygon, an internal region thereof, and such. These processes are collectively referred to as a geometry process, since both of the processes mainly include a geometrical process for arranging a polygon mesh in a virtual space so as to project the polygon mesh on a screen. This geometry process is a bottleneck in rendering a polygon mesh.
Patent Document 1 discloses a method for performing the vertex process and the polygon process, with use of a plurality of processors so as to perform the geometry process at high speed. According to this method, processors that perform the vertex process are different from processors that perform the polygon process. The vertex process is performed for each vertex by a plurality of processors in parallel. A result obtained by the vertex process is transmitted to a main processor.    Patent Document 1: Japanese Laid-Open Patent Application No. 11-328436